Oil-fired coke ovens and method of firing



Sept. 12, 1967 H. JOHNSON ETAL OIL-FIRED COKE OVENS AND METHOD OF FIRING Filed Jan. 25. 1963 Horgce Johnson Leslle Henry Wollus Savage INVENTORS By W @Q/(M I Patent Attorney United States Patent ()fiFice 3,341,635 Patented Sept. 12, 1967 OF FIRING Sunbury-on-Thames, and Leslie H. W.

England, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Jan. 25, 1963, Ser. No. 254,551 Claims priority, application Great Britain, Jan. 26, 1962, 3,035/62 2 Claims. (Cl. 263-52) This invention relates to the operation of coke ovens, and in particular relates to a method of heating coke ovens with liquid fuels.

Coke ovens provide for the carbonisation and dry distillation of coal, lignite, peat or mixtures thereof, either in particulate or briquetted form, and consist essentially of a number of retort chambers for holding the carbonaceous solids, separated from each other by a series of long narrow vertically disposed flues. The flues have hitherto been fired under industrial conditions with normally gaseous fuels, for instance with coke oven gas or blast furnace gas, or other gas containing combustible components. In such installations the combustion gases are introduced into the combustion flues through upwardly-directed nozzles at the bottom of the flues, and mixed with combustion air to provide heat for the carbonisation process to take place in the adjacent retorts. Conventional design allows the hot flue gases to pass through cross-over flues to an adjacent combustion flue which is thereby heated, the flow of combustion gases through the flue systems being periodically reversed to conserve heat requirements according to wellknown practice.

The invention consists in the use of normally liquid fuels in coke-ovens, in that the liquid fuels are introduced into the combustion chamber and are burnt therein. By this means the necessity of providing a controlled mixture of gases for the combustion flues is avoided, and greater control may be provided over the heating of the retorts, and further there is a conservation of valuable prouct gases which would otherwise be required to be recycled to the combustion zone of the flues.

To provide high quality coke from the carbonisable substance in the retort, for instance metallurgical coke, it is highly desirable that the combustion of the liquid fuel shall be arranged so as to provide as even a temperature distribution as possible throughout the combustion flues. One embodiment of the invention provides for the continuous injection of a stream of liquid fuel into the combustion flue through one, or preferably two or more atomizing nozzles separated at spaced intervals along the length of the combustion flue. The use of an atomizing nozzle, preferably disposed to form a suspended flame, inhibits the formation of carbon particles within the combustion zone. A further modification using a continuous stream of liquid in the combustion zone is that the liquid fuel is injected alternately through one or more nozzles in the lower and upper regions of the vertical combustion flue, thus providing a cyclic heating action in the lower and upper reaches and achieving an approximation of even heating along the length of the flue.

A preferred method of putting the invention into effect is by pulse injection of liquid petroleum fuels into the top of the combustion flues, by providing at the top of the combustion flues fuel oil injection means adapted to deliver slugs of fuel oil at periodic intervals at predeter- Horace Johnson,

Savage, Hounslow,

mined volume and velocity, whereby the slugs of oil travel down the flue and are completely burnt with combustion air passing upwardly and countercurrently therethrough. By this means the long lazy flame characteristics obtained with conventional "gas burners are obtained with liquid fuel oil.

The fuel oil injection means may conveniently include an injection tube or lance directed downwardly into the combustion flues, and associated with control means whereby the oil slugs are delivered into the combustion flues through the injection tube or lance. Thus a pump may be provided to give the desired overall fuel oil feedrate at a predetermined pressure, the flow of oil through the lances being broken into pulses with the aid of periodically operating actuating valve means. The fuel oil injection means in dead combustion flues are turned oflf until the flow of combustion air is reversed.

The fuel oil used in this invention may be any liquid fuel derived from petroleum, coal, lignite or shale fuel oil, including naphtha, gas oils or blends thereof, and particularly petroleum residual fuel oil such as Bunker C fuel oil.

In the accompanying drawing there is illustrated a schematic arrangement for a conventional coke oven adapted for pulse injection according to the invention, wherein retort chambers l are heated by arrays of combustion flues 2, each having a relatively narrow inspection chamber 3. Means for introducing combustion air into the lower end of the combustion flues from regenerators 4 are provided but not shown. At the top of the inspection port 3 an injection lance 5 is provided for the introduction of liquid fuel into the flue, held in position in an inspection cover 6.

Pulse injection of the liquid fuel may be provided by an arrangement consisting of a storage tank 7 delivering liquid fuel via line 8 through a pump 9 to a metering valve 10 to one side of a piston 11 contained therein. A bleed fuel line 12 leads to the other side of the piston, which is actuated by valves 13, 14 and 15 to deliver pulses of liquid fuel under pressure to the lance 5 through line 16. The valves 13, 14 and 15 may be actuated by any suitable mechanical pneumatic, hydraulic or electrical device not shown, to regulate the frequency of the pulses delivered.

Typical coke oven installations provide a plurality of retort chambers each capable of holding about 1020 tons of carbonaceous material, and heated by adjacent rows of vertical flues, each flue having a heating zone of approximately 10-20 feet high, and having a crosssectional area of about 1 to 2 square feet. In such installations the energy requirement using a Bunker C type fuel to maintain a coking temperature of 1250 C. to carbonise 12 tons of coal per retort in 24 hours may be provided by a fuel injection rate of 7 gals/hour over the coking period. For a typical installation containing 28 combustion flues in each array of flues (of which 14 will be fired at any one time), this means that for the above conditions about 0.4 gaL/hour of residual fuel oil should be injected into each flue. Using the pulse injection technique hereinbefore described, the overall feedrate of fuel may be provided by injecting pulses of residual fuel oil at a rate of 4 to 24 pulses per minute, each pulse providing from 2 to 12 cc. of fuel. The actual pulse rate and volume of each pulse will depend on the particular dimensions of the flue, the temperature of combustion required and the calorific value of the liquid fuel used. The pulse volume should preferably be adjusted however so that each slug of 'oil continues to'burn as it travels down the length of the flue countercurrent to the flow of combustion air, and is consumed completely by the time it reaches the bottom of the flue.

What is claimed is:

1. The method of firing coke ovens containing vertical combustion flues comprising pulse injecting slugs of liquid fuel downwardly into the tops of said combustion flues at a predetermined volume and frequency and introducing combustion air upwardly through said combustion flues so that said slugs of fuel continue to burn as they travel,

down the vlength of flames.

' 2. A coke oven comprising in combination:

(a) a plurality of vertical combustion flues;

the flue, thereby producing long (b) a lance positioned'n the top of each of said fines,-

said lance adapted tosupply liquid fuel in a downward direction; and

(0) means operatively connected to each said lancev for delivering liquid fuel to each lance in pulses whereby each lance injects slugs of liquid fuel into its flue. 5 References Cited UNITED STATES PATENTS 1,099,932 6/1914 Pieter 202139 XR 1,847,199 3/1932 Van Ackeren 202--126-XR 1,919,098 7/193'3 Duckham r l 202-140 10 1,935,298 11/1933 Richardson 263-52' 3,170,851 2/ 1965 Van Ackeren 202139 X FOREIGN PATENTS 746,199 3/ 1956 Great Britain.

MORRIS O. WOLK, Primary Examiner.

JOSEPH SCOVRONEK, Examiner. 

1. THE METHOD OF FIRING COKE OVENS CONTAINING VERTICAL COMBUSTION FLUES COMPRISING PULSE INJECTING SLUGS OF LIQUID FUEL DOWNWARDLY INTO THE TOPS OF SAID COMBUSTION FLUES AT A PREDETERMINED VOLUME AND FREQUENCY AND INTRODUCING COMBUSTION AIR UPWARDLY THROUGH SAID COMBUSTION FLUES SO THAT SAID SLUGS OF FUEL CONTINUE TO BURN AS THEY TRAVEL DOWN THE LENGTH OF THE FLUE, THEREBY PRODUCING LONG FLAMES. 